Black springs should work just fine as long as they are longer than the bolt itself. Yes clean them you dont want rust flakes/dust floating around inside the body.
If the dent in the body is all the way at the open end, try using a tapered pin or bull pin to knock it out. Heres an example. Klein Tools Broad Head Bull Pin — 10in. x 1 1/16in. Top Dia., 1/4in. Point Dia., Model# 3256 | Flex + Ratcheting Wrenches | Northern Tool + Equipment